A car is driving directly north on the freeway at a speed of 115 km/h and a truck is leaving the freeway driving 86.6 km/h in a direction that is 35° west of north. Assume north to be in the +y-direction and east to be in the +x-direction. What is the magnitude of the velocity of the truck relative to the car?

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Chapter1: Units, Trigonometry. And Vectors
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## Problem Statement

A car is driving directly north on the freeway at a speed of 115 km/h, and a truck is leaving the freeway driving 86.6 km/h in a direction that is 35° west of north. Assume north to be in the +y-direction and east to be in the +x-direction.

### Question:
What is the magnitude of the velocity of the truck relative to the car?

### Detailed Explanation:

1. **Car's Velocity:**
   - The car is traveling directly north with a velocity \( \vec{v_c} \) of 115 km/h.
   - Since north is defined in the +y-direction, we represent the car's velocity vector as:
     \[
     \vec{v_c} = 0\,\hat{i} + 115\,\hat{j} \, \text{km/h}
     \]
     where \( \hat{i} \) and \( \hat{j} \) are the unit vectors in the x (east) and y (north) directions respectively.

2. **Truck's Velocity:**
   - The truck is moving 35° west of north with a velocity \( \vec{v_t} \) of 86.6 km/h.
   - We need to resolve this velocity into its x and y components. 
     - The y-component (north component) is \( 86.6 \cos(35°) \).
     - The x-component (west component, negative x-direction) is \( -86.6 \sin(35°) \).

     Thus, the truck's velocity vector in component form is:
     \[
     \vec{v_t} = -86.6 \sin(35°)\,\hat{i} + 86.6 \cos(35°)\,\hat{j}
     \]

3. **Relative Velocity:**
   - The velocity of the truck relative to the car \( \vec{v_{t/c}} \) is given by the difference between the truck’s velocity and the car’s velocity:
     \[
     \vec{v_{t/c}} = \vec{v_t} - \vec{v_c}
     \]

   - Substituting the values:
     \[
     \vec{v_{t/c}} = (-86.6 \sin(35°)\,\hat{i} + 86.6 \cos(35°
Transcribed Image Text:## Problem Statement A car is driving directly north on the freeway at a speed of 115 km/h, and a truck is leaving the freeway driving 86.6 km/h in a direction that is 35° west of north. Assume north to be in the +y-direction and east to be in the +x-direction. ### Question: What is the magnitude of the velocity of the truck relative to the car? ### Detailed Explanation: 1. **Car's Velocity:** - The car is traveling directly north with a velocity \( \vec{v_c} \) of 115 km/h. - Since north is defined in the +y-direction, we represent the car's velocity vector as: \[ \vec{v_c} = 0\,\hat{i} + 115\,\hat{j} \, \text{km/h} \] where \( \hat{i} \) and \( \hat{j} \) are the unit vectors in the x (east) and y (north) directions respectively. 2. **Truck's Velocity:** - The truck is moving 35° west of north with a velocity \( \vec{v_t} \) of 86.6 km/h. - We need to resolve this velocity into its x and y components. - The y-component (north component) is \( 86.6 \cos(35°) \). - The x-component (west component, negative x-direction) is \( -86.6 \sin(35°) \). Thus, the truck's velocity vector in component form is: \[ \vec{v_t} = -86.6 \sin(35°)\,\hat{i} + 86.6 \cos(35°)\,\hat{j} \] 3. **Relative Velocity:** - The velocity of the truck relative to the car \( \vec{v_{t/c}} \) is given by the difference between the truck’s velocity and the car’s velocity: \[ \vec{v_{t/c}} = \vec{v_t} - \vec{v_c} \] - Substituting the values: \[ \vec{v_{t/c}} = (-86.6 \sin(35°)\,\hat{i} + 86.6 \cos(35°
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